The C or the S with corp actually refers to the appropriate subchapter of the federal tax code. When filing with the state, a corporation is neither filed as a C corp or an S corp, but just as a corporation, so they start out identical on the state level. The IRS treats all corporations (for purposes of federal taxation) as a C corp by default. All that needs to be done to be taxed as an S corporation is that once the corporation is filed with the state, then the subchapter S election form must be submitted within 75 days of the date of formation of the corporation. Please follow the link below if you would like to order Form 2553 for election for S-Corp status with the IRS.